碳离子注入辅助在6H-SiC表面制备石墨烯

为了寻找一种更便捷、更经济的在半导体SiC基底上直接生长石墨烯的方法, 将5 keV C离子注入商用6H-SiC(0001)单晶, 通过拉曼光谱、扫描电子显微镜(SEM)和原子力显微镜(AFM)表征研究石墨烯质量和生长过程。实验中还研究了不同降温速率以及石墨舟的封闭环境对石墨烯生长的影响, 并基于Si原子的蒸发提出一个可能的生长机制。结果表明, 封闭的石墨舟可以有效地限制Si原子的蒸发, 降温速率会影响C原子的析出和表面自组装, 合适的降温速率可以使注入的C原子在表面析出, 从而直接在6H-SiC表面自组装形成双层至多层石墨烯。该方法能够将制备温度降至1100℃, 制备过程不需要氢刻蚀、超高真空或特殊气氛条件, 过程简单, 降低了对仪器设备的要求。

Direct Synthesis of Graphene on 6H-SiC Assisted by Carbon Ions Implantation

In order to provide a more convenient and economical approach of graphene synthesis on semiconducting 6H-SiC, commercially available single crystalline 6H-SiC samples were implanted at room temperature with 5 keV carbon ions. The prepared samples were characterized by Raman spectroscopy, scanning electron microscope (SEM) and atomic force microscope (AFM). Moreover, the influences of cooling rates and the enclosed environment were investigated. A possible growth mechanism based on the Si sublimation was also put forward to explain the graphene growth. The results show that the graphite enclosure effectively control the Si sublimation and the cooling rate affects the precipitation and surface self-assembly of C atoms. Upon proper cooling, the implanted carbon atoms segregate to the surface and self-assemble into bilayer or multilayer graphene on 6H-SiC. This method reduces the annealing temperature to 1100℃ in vacuum condition without hydrogen etching, ultrahigh vacuum or special atmosphere, which is more cost-effective and efficient.